The present invention relates to internal combustion engines, such as spark ignition and diesel engines. More particularly, the invention contemplates systems and methods for direct conversion of combustion pressure to drive engine pistons.
Combustion pressure and temperature knock limits are responsible for major heat losses in all current internal combustion engines. All combustion is progressive, whether originating from spark ignition or minimum temperature auto-ignition. When combustion occurs, the progressive flame expands from the point of ignition as the temperature rises. When the burn energy rate exceeds the heat transfer rate, the temperature within the engine cylinder rises exponentially until explosion expansion of all the end gas occurs. This explosion expansion generates a high-pressure spike followed by instant collapse. This event yields the xe2x80x9cengine knockxe2x80x9d phenomenon. Heretofore, engine knock control has been limited to reducing compression pressure or using high-octane fuel.
Combustion at the minimum temperature of auto-ignition, between 400-600xc2x0 C., does not produce knock if expansion yield can limit peak pressure. Increasing yield works to prevent knock, so providing additional constant volume gas yield above minimum temperature auto-ignition can increase the expansion rate until all the fuel is burned, even above 600xc2x0 C.
This latter principle was employed in my earlier invention, as described in U.S. Pat. No. 6,035,814, issued on Mar. 14, 2000. In particular, this patent described my xe2x80x9crocket pistonxe2x80x9d for use in an internal combustion engine. In this invention, the rocket piston operated against bounce gas behind the piston. In accordance with the invention, the bounce gas would speed up yield at limited pressure until all the end gas within the cylinder is burned, making engine knock impossible within the combustion cavity. With this rocket piston expansion, instant conversion of all the high-pressure auto-ignition expansion to peak pressure with more rapid yield decimates heat loss, while insuring maximum combustion power. Under these conditions, all of the combustion gas expands adiadatically, with practically no fire during expansion to exhaust.
Internal combustion engines were greatly improved when they changed from burning fuel to make steam to direct conversion of combustion pressure to drive engine pistons. However, the crank-controlled piston, which is near ideal for steam, is too slow to match acceleration auto-ignition rates above 600xc2x0 C., causing exponential expansion engine knock Knock may be controlled with limited pressure or faster yield rates at high pressure obtained by the rocket piston gas cushioned energy expansion accumulator at higher temperatures. Thus, all current internal combustion engines must use high octane fuel or lower compression ratios, losing over eighty percent of heat combustion energy during city traffic driving at part throttle because the hot combustion gas just sits until slow piston motion expands the charge. Moreover, medium pressure combustion flame temperatures toast engine exhaust gas thus forming nitrous oxide (NOx) pollution that must eventually be removed by a catalytic converter.
All fuel-injected engines have some evaporated air-fuel mixture for spark ignition, and some liquid fuel can always wet the piston crown and ports. This fuel is ignited by flame evaporation and progressive auto-ignition burning as the rocket piston yields. This principle is employed for all engines including supercharged and improved diesel engines using the rocket piston and fuel injection. My prior rocket piston has taken a large step in producing direct conversion as fast as the fuel can burn speeding up yield rate above combustion expansion rate near top-dead-center, with no slow flame that can form NOx air pollution.
The addition of the rocket piston gas cushion yield in the combustion cavity provides instant conversion of all the combustion gas above the combined compression gas and bounce gas volumes; with near 100% efficiency as the rocket piston reciprocates with substantially no friction and transfers peak pressure and temperature energy through the thin wall piston. The bounce gas yield and instant conversion expansion provides the bonus power, and operates as a knock limiter through the fast gas-to-gas addition to the engine cycle. The rocket piston remains seated during the scavenge stroke. The lift off pressure is higher than the seating pressure due to valve area hysteresis.
In accordance with the present invention, an improvement to the crank piston for reciprocating operation within a cylinder of any internal combustion engine is provided. In one aspect of the invention, this improvement comprises a short cylinder defining a recess under a piston crown port plate closing the recess to define a bounce gas chamber therein. The plate defines a plurality of ports or openings therethrough for permitting communication of combustion gas between the engine cylinder and the chamber above a rocket piston disc disposed within the short cylinder.
In another feature, a rocket piston disc sized to reciprocate within the short cylinder operates beneath the port plate closing the ports. The piston disc translates in response to combustion gas passing through the ports. The disc operates as a rocket piston disc by first trapping a fraction of peak pressure in bounce gas between the disc and the bottom of the cylinder, compressing this bounce gas in response to auto-ignition gas pressure exerted through the ports, then providing supplemental crank power as the rocket piston disc translates upward to seat, trapping a fraction of peak pressure plus valve seat hysteresis area for the next cycle.
In one embodiment, a support member in the form of a conical spring can be provided to hold the rocket piston near a seat in the port plate. The spring force rate may be increased to raise bounce pressure if desired.
Preferably, the crown plate defines about twenty-one (21) ports or openings therethrough large enough to avoid quenching the flame for non-quenching free flow. In one embodiment, the plate includes one opening at its center, with the remaining openings uniformly distributed around the plate. In another embodiment, particularly for use with center fire injectors, the center opening may be eliminated.
The rocket piston disc is preferably formed of a heat-resistant metal. For example, the disc can be composed of chrome-nickel, stainless steel, or titanium material. Preferably, the disc has a thickness of about 0.05-0.06 inches (1.27-1.52 mm.). The weight of the disc is preferably in the range of about 0.176 lbs. for a stainless steel rocket piston, and about 0.079 lbs. for a titanium 4.0 inch piston.
In operation, combustion gas passes through the ports in the top plate to exert pressure against the rocket piston disc. When combustion pressure exceeds the trapped bounce gas pressure force beneath the piston disc, the rocket piston disc lifts off its seat with rapid acceleration and nearly perfect balance with practically no leak or friction. Trapped expansion pressure rises to peak combustion pressure, then all the transferred compression energy recycles, driving the crank piston with about 100% efficiency until the rocket piston disc re-seats. The efficiency is appreciably higher than any other engine design because the piston disc reciprocates with essentially no friction and in part because the heat transfer through the rocket piston disc to the bounce gas is greater than the heat loss to the crank piston through the bounce gas.
It is one object of the invention to provide an engine crank piston with an additional instant conversion rocket piston bounce gas in a short cylinder cushion in the top of the crank piston, to provide primary yield rates matching combustion expansion rates making knock impossible while burning all the end gas fuel for power in one millisecond.
It is a further object of the invention to provide an engine piston capable of achieving greater thermal and combustion efficiency by instant conversion to bounce gas compression by one millisecond. Another object is to provide an internal combustion engine cylinder cycle that minimizes or eliminates various pollutants, such as NOx emissions which are not formed in one millisecond flame time.
It is one object of the invention to provide a Bellville spring to increase the bounce pressure to always match any peak pressure. The addition of the additional constant volume bounce gas cushion and rocket piston check valve provides additional constant volume yield above minimum temperature auto-ignition high pressure for maximum constant volume efficiency and faster yield until all the end gas is burned. This yield is never exceeded by combustion expansion making knock impossible at high pressure and permitting instant conversion of all the flame expansion energy until all the end gas fuel is burned early in the cycle to accommodate any homogeneous or heterogeneous engine cycle.
These and other objects and benefits will become apparent upon consideration of the following written description together with the accompanying figures.